Now I can't tell you about this wall in particular, but my understanding is that at Machu Picchu the stone work was originally all fitted without mortar, with huge stones of this size and that each stone was individually tailored to fit with its neighbours. I'm not sure if the walls in Cuzco were the same, but this wall lines one alley through which tourists are funnelled, so everyone gets to see it. It may be a reconstruction, a renovation or whatever, but it illustrates, I believe, an example of the original skill of the locals. The concept is amazing and the reality must have been stupendous. Machu Picchu was abandoned when the Spaniards came rolling in. I don't think they (the Spaniards) actually found it. You get an idea of scale from the people in the alley.